Superstrings

Minutes

President Agger called the 2093rd meeting to order at 8:20 p.m. on September 18, 1998. The Recording Secretary read the minutes of the 2092nd meeting and they were approved.

The speaker for the 2093rd meeting was Sylvester James Gates, the John Toll Professor of Physics at the University of Maryland. The title of his talk was, “Superstrings: Why Einstein Would Love Spaghetti in Fundamental Physics.”

There are questions in physics that until recently could not be answered due to the lack of a complete theory of gravitation. These questions include: “How does gravity work on objects a billion billion times smaller than the hydrogen atom?” “What was the universe like at the instant after the Big Bang?” and “What is the complete physics of Black Holes?” To answer such questions it is necessary to know how the force of gravity is consistent with the principles of quantum theory and the physical axioms that govern the tiniest objects in our universe.

In these arenas, the effects of gravity and all the other forces must be very different from those seen in our everyday experience. Einstein suspected this, and it led him to the belief that there must exist a “Unified Field Theory” to describe our world. He spent the last forty years of his life unsuccessfully searching for it. Recently however, there appeared new ideas described as part of a “Superstring Theory” that have apparently succeeded in this noble quest. The theory was developed by combining the disciplines of mathematics and theoretical physics of supersymmetric particles with fields and strings. It addresses the topics of quarks, leptons, gravity, and unified field theories of the type first envisioned by Einstein.

Gravity, the force that holds us to the earth and the earth in its orbit, is one of four fundamental forces in our universe. The others are the weak nuclear force which is the driving force of natural radioactive material, the electromagnetic interaction force which is the force of electromagnetism, and the last is the strong interactive force which provides the sun's source of energy. Traditionally, the gravitational force between any two bodies is directly proportional to the mass of the bodies and inversely proportional to the square of the distance between them. However, this approach stumbles at great distances because it does not accommodate time. For example, if we move something on earth, we don't instantly impact the pull on Alpha Centauri. Something was amiss.

To help resolve the issue of our limited gravity model, Mr. Gates presented a thought experiment to describe his thesis. Historically, we have cut things apart to their smallest element of matter. We started with the atom, which was found to consist of protons and neutrons and then yielded quarks and leptons. Each time, the smallest unit was considered to be a point particle visualized as a tiny ball. The last premise of the tiny ball provided the long sought after flaw; that is: it simply may not be true that the smallest unit is a tiny ball. The most fundamental unit according to the string conjecture is a really like a piece of spaghetti, hence Mr. Gates' title of his talk involving Einstein and his love for spaghetti. That's the end of the story. A string! It's also the beginning of the story.

If the string models are correct, why didn't the ancient Greeks think of them? The answer is that point-based theories worked great until Einstein. The smallest elements of matter conceived of acted like and could be effectively described as a point and its size didn't really matter. However, it turns out that size does in fact matter. Consider a man to be on the order of one meter in height, next consider an atom as ten orders smaller or 10-10 meters, next a proton as fifteen orders smaller at 10-15 meters, finally our strings as 34 orders smaller at 10-34 meters.

Stings allow some interesting properties to be considered beyond that of a tiny ball or point. For example, whereas a point sweeps out a line as it moves, a sting sweeps out a surface. Further, the ends of a string can be tied together and the tied up loop will sweep out a tube, or a “world sheet.” Further, a spinning string is a “Superstring.” Finally, unlike a ball-shaped fundamental particle, a string can behave like a musical instrument where different string vibrations make chords and the different chords describe the all the fundamental particles we have come to know such as quarks and leptons. Further, the many chords also describe particles we haven't seen yet, such as “selectrons.” The search for these as yet unseen particles, as well as new forms of energy, such as “photinos,” remains for the next chapter in this fascinating story. Mr. Gates then closed his presentation and kindly answered questions from the floor.


President Agger thereupon thanked Mr. Gates for the society, announced the next meeting and made the usual parking announcement. She then adjourned the 2093rd meeting to the Social Hour at 9:40 p.m.

Attendance: 73
Temperature: 17.4°C
Weather: clear

Respectfully submitted,

Bill Spargo
Recording Secretary